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  • Title: [Dynamic changes in depolarization of action potentials by high frequency stimulation in guinea pig papillary muscles].
    Author: Shen WQ, Xu XY, Zhao WW, Duan-Mu ZX, Yu ZM, Yu XM, Wang LY, Zhang LY.
    Journal: Zhongguo Yao Li Xue Bao; 1989 Jul; 10(4):332-5. PubMed ID: 2624118.
    Abstract:
    The effect of high frequency stimulation on rate-dependent depression of depolarization of action potentials was studied with computer and standard microelectrode techniques in guinea pig papillary muscles. After increasing driving frequency from 0.5 to 6 Hz, decreases in Vmax, APA and OS were found. Changes of upstroke velocity during phase 0 between driving frequency 6 and 0.5 Hz could be described as a parabola. The rate-dependent depression of depolarization was exaggerated by tetrodotoxin (TTX), particularly during the accelerating period of phase 0. A progressive decline in Vmax, which could be fitted by a power function curve, was observed after changing driving frequency from 1 to 5 Hz. TTX significantly influenced the decline in Vmax and the regression coefficients in fitted equations.
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